Heating, Ventilation and Shading For Succulents

The greenhouse must have some provision for heating in winter, to maintain a minimum temperature of at least 4° C. (40° F.). Temperatures below this are harmful to most succulents, and some prefer a higher winter temperature. It is simpler, perhaps, to keep such plants in a different house or at least well separated from others. Where lower winter temperatures are desirable as with some cacti which flower less freely, if not kept cold at this season, this is indicated in the alphabetical list of succulent genera.

For heating a small house the common paraffin heater may be used, with the usual care to prevent fumes, which may damage plants. Hot-water pipes heated by a boiler are standard in many houses, and are quite efficient but tedious to maintain. Electric tubular heating, controlled by a thermostat, is the ideal. It is relatively cheap to install and at 4 – 8° C. (40 – 470 F.) reasonably cheap to run; the thermostat prevents waste, often difficult to achieve with boilers, and there is little maintenance or worry involved.

Succulents always like fresh air, and should be given as much as possible, winter and summer, as long as the weather is suitable. In winter, ventilators should be opened by day as long as the required temperature is maintained, and there is no fog or mist. Draughts must be avoided: therefore those ventilators away from the wind must be opened — another reason for having plenty of them.

As spring progresses, there will be less need to heat the house; but watch must be kept for sudden cold spells and frosty nights, particularly if a previous warm spell has started the plants into growth. It is here that an automatic heating system scores.

In warm weather the main thing to watch is ventilation. On hot, still days all the vents can be opened. If it is windy those on the windward side are closed, for even in summer draughts should be avoided. Movement of air is necessary though, especially if the weather is damp and the air moist. In a variable climate some closing of vents at night is advisable to guard against a change of wind direction or driving rain.

The mechanisms that open and close ventilators as the temperature fluctuates are valuable, especially if the house has to be left unattended.

Shading

Most succulents do not require much shading, though under glass, in very bright weather with no air movement, yellowing or scorching may occur if temperatures go over 270 C. (80° F.). All highly adapted forms need maximum sunlight at all times, and the glass must be kept clean to ensure this. Only a few must be shaded; they include the epiphytic cacti. Where a plant requires shading, this is stated in the list of succulent genera.

The best means of shading such plants is a thin film of whitewash with a very little linseed oil, on the outside of the glass; commercial materials are too thick.

When sunlight is weak and infrequent in winter, as much as possible must reach our plants. Therefore the glass should be well washed in autumn, and this should be repeated as and when necessary, particularly in towns where grime soon films the glass.

Staging

As with any kind of pot plant, succulents should be placed on the staging so that they are graded in size from front to back, ensuring that they all receive equal amounts of light and that they are easily reached.

A small shelf at the back of the staging may be useful for display if the collection consists mostly of little plants, and also to place hanging-type plants on. Alternatively, such plants can be placed on an inverted pot.

Some growers bury their pots up to the rims in a deep bed of grit or gravel. This is, in fact, advisable with the small Aizoaceae and other tricky plants, since the bed is watered, not the pots, and the dangers of direct watering are avoided. The roots emerge from the drainage holes and seek moisture in the bed of grit. Of course, plants with different resting periods must be kept well apart.

This is admirable if one does not want to take the plants to shows, and if one has the patience to leave a semi-permanent arrangement alone. It permits a more naturalistic display, and the ‘stone-imitating’ plants, for instance, can be grouped with similar stones to demonstrate their camouflage. Small grit is placed over the whole surface, hiding the pot rims and giving a natural-looking finish.

Direct planting into the soil cannot be recommended unless the arrangement is to be well-nigh permanent.